For example, a fastener is used in mounting a member to be mounted or a mounted member such as an insulator or a garnish on a mount member such as a body panel or a body frame of a motor vehicle.
As a conventional fastener of this type, Patent Document 1 below describes a clip which includes a head portion which is provided on one surface side of a base plate, a pillar portion which is provided on the other surface side of the base plate so as to be erected therefrom, a pair of permanent fixing engaging projections provided on the pillar portion for engagement with a permanent fixing mounting hole and a pair of temporary fixing elastic arms which are provided at a distal end of the pillar portion so as to extend therefrom in a cantilever-like fashion for engagement with a temporary fixing mounting hole which is opened wider than the permanent fixing mounting hole on a base plate side thereof. Additionally, the pair of temporary fixing elastic arms are shaped so that proximal end portions project from an outer circumference of the distal end of the pillar portion to extend obliquely outwards as arms of an anchor do towards the head portion. Further, distal end portions of the temporary fixing elastic arms are bent substantially into a collapsed V-like shape so as to move towards each other, and the distal end portions are made into thin portions (refer to FIGS. 1 and 2 of Patent Document 1).
Then, when in a state in which the clip is temporary fixed to an interior material, the head portion is brought into abutment with a front side of the temporary fixing mounting hole, and the distal end portions of the pair of temporary fixing elastic arms are brought into engagement with a circumferential edge of a rear side of the temporary fixing mounting hole, whereby the clip is temporarily fixed to the interior material (refer to FIG. 5). When the pillar portion of the clip is inserted into the permanent fixing mounting hole in the body panel in that state, proximal portion sides of the pair of temporary fixing elastic arms are pressed against an inner circumference of the permanent fixing mounting hole to thereby be contracted radially inwards, and the distal end portions thereof are deformed so as to be bent out of shape, whereby the pillar portion of the clip is disposed in the inner circumference of the permanent fixing mounting hole. Further, since the pair of permanent fixing engaging projecting portions are brought into engagement with a circumferential edge on a rear side of the permanent fixing mounting hole, the interior material is mounted on the body panel via the clip (refer to FIG. 6 of Patent Document 1).